الفهرس 
LITERATURE REVIEWOnly 14 pages are availabe for public view
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Abstract
This research investigates the behavior of composite column formed from double cold-formed sigma sections (face to face) as steel shell tubes. Sixteen specimens with different lengths, cross-section dimensions and cross section thicknesses were tested experimentally under both concentric and eccentric compressive load. Ultimate capacities, lateral deformations and axial strains were recorded. In order to investigate the composite actions between the steel tube and concrete core, 3-D FEM models are developed and verified against experimental results in terms of failure modes, load-deformation curves and ultimate loads. The verified FEM models were used to carry out a parametric study to study the effect of varying shell thickness (t), cross-sections, load eccentricity (e), and column length (L) on the behavior of the column. The study results indicated that Global buckling dominated the failure modes for specimens with global slenderness ratio (λ) more than 85. Short specimens with global slenderness ratio (λ) less than 50 failed due to local buckling. The reduction of the axial capacity of the sections due to buckling was about 20% regardless it is aspect ratio where the slenderness ratio (λ) is valid between 50 to 150. Failure in big eccentricity loaded columns (e/d=0.5) was flexural for sample with aspect ratio of 1.5 & 2.0. Finally, both experimental and FEM capacities were compared with capacities using interaction diagram besides three design codes, namely ECP 205 (ASD & LRFD) and EC4. The comparison illustrated that the interaction diagram was the closest to the experimental results with error percent of (13%), and EC4 code came in the second order with error percent of (19%), then ECP 205 (LRFD) with error percent of (30%) and finally ECP 205 (ASD) with error percent of (90%).
Keywords: Cold formed; Composite columns; Sigma sections; In-filled Column